Numerous applications exist in which it is desired to form repeating patterns having a small pitch (for example, a pitch of less than about 50 nanometers). For instance, integrated circuit fabrication may involve formation of a repeating pattern of memory-storage units (i.e., NAND unit cells, dynamic random access memory [DRAM] unit cells, cross-point memory unit cells, etc.).
A variety of methods have been developed for creating patterned masks suitable for patterning underlying materials during fabrication of integrated circuit components. A continuing goal of integrated circuit fabrication is to increase integrated circuit density, and accordingly to decrease the size of individual integrated circuit components. There is thus a continuing goal to form patterned masks having increasing densities of individual features. In cases in which the patterned masks comprise repeating patterns of features, there is a continuing goal to form the repeating patterns to higher density, or in other words, to decrease the pitch.
A method showing some promise for creating repeating patterns to high density involves utilization of a copolymer to form a repeating pattern. Unfortunately, there are often numerous defects present in the repeating patterns formed with copolymers. It would be desirable to develop new methods of forming patterns with copolymers which enable repeating patterns to be formed to high density, and with fewer defects than are presently formed with conventional methods.